This invention relates generally to radio frequency (RF) signal frequency down converters and more particularly to dual channel RF signal frequency converters.
As is known in the art it is generally required to convert received radio frequency (RF) signals into intermediate frequency signals. In some applications, as for example direct broadcast satellite systems, in order to increase the number of signal channels within a prescribed bandwidth, information in pairs of channels share a common frequency band. The information in pairs of channels is transmitted as a composite RF signal having the common frequency band. The information in one of the pair of channels is transmitted with one type of polarization, say horizontal polarization, while the information in the other one of the pair of channels is transmitted with a different type of polarization, say vertical polarization. Thus, the number of channels within the prescribed frequency band is doubled.
It follows then, that a receiving system must, in addition to down converting the RF frequency of the received RF composite signal to an intermediate frequency, direct one polarized signal to one receiver channel and the other polarized signal to the other receiver channel.